Really straightforward with the GS - since most, if not all, of the troubles start with bad and corroded connections, both in the loom (bullet connectors) or in the switchgear (strip and clean). Once you're sure of how clean they are, you've got a starting point. A decent voltmeter will tell you what's going on. On the GS Resources site, the recommendations of posplayer about making a single-point ground are worth doing. If at the very least, you follow his Quick Test routine, you'll know what's what with your system. I'd thoroughly recommend replacing the reg-rec with the aforementioned series unit from Polaris, as it's only a matter of time before your stator is taken out, usually at the most inconvenient tiime, too. Seriously, if series reg-recs had been around 35 years ago, the GS range would never have developed the reputation for dodgy electrics that it did.